Genomic insights into rapid speciation within the world’s largest tree genus Syzygium
Yee Wen Low, Sitaram Rajaraman, Crystal M. Tomlin, Joffre Ali Ahmad, Wisnu H. Ardi, Kate Armstrong, Parusuraman Athen, Ahmad Berhaman, Ruth E. Bone, Martin Cheek, Nicholas R. W. Cho, Le Min Choo, Ian D. Cowie, Darren Crayn, Steven J. Fleck, Andrew J. Ford, Paul I. Forster, Deden Girmansyah, David J. Goyder, Bruce Gray, Charlie D. Heatubun, Ali Ibrahim, Bazilah Ibrahim, Himesh D. Jayasinghe, Muhammad Ariffin Kalat, Hashendra S. Kathriarachchi, Endang Kintamani, Sin Lan Koh, Joseph T. K. Lai, Serena M. L. Lee, Paul K. F. Leong, Wei Hao Lim, Shawn K. Y. Lum, Ridha Mahyuni, William J. F. McDonald, Faizah Metali, Wendy A. Mustaqim, Akiyo Naiki, Kang Min Ngo, Matti Niissalo, Subhani Ranasinghe, Rimi Repin, Himmah Rustiami, Victor I. Simbiak, Rahayu S. Sukri, Siti Sunarti, Liam A. Trethowan, Anna Trias-Blasi, Thais N. C. Vasconcelos, Jimmy F. Wanma, Pudji Widodo, Douglas Siril A. Wijesundara, Stuart Worboys, Jing Wei Yap, Kien Thai Yong, Gillian S. W. Khew, Jarkko Salojärvi, Todd P. Michael, David J. Middleton, David F. R. P. Burslem, Charlotte Lindqvist, Eve J. Lucas & Victor A. Albert
Date:
2022-09-12
Abstract:
Species radiations, despite immense phenotypic variation, can be difficult to
resolve phylogenetically when genetic change poorly matches the rapidity of
diversification. Genomic potential furnished by palaeopolyploidy, and relative
roles for adaptation, random drift and hybridisation in the apportionment of
genetic variation, remain poorly understood factors. Here, we study these
aspects in a model radiation, Syzygium, the most species-rich tree genus
worldwide. Genomes of 182 distinct species and 58 unidentified taxa are compared
against a chromosome-level reference genome of the sea apple, Syzygium
grande. We show that while Syzygium shares an ancient genome doubling event
with other Myrtales, little evidence exists for recent polyploidy events. Phylogenomics
confirms that Syzygium originated in Australia-New Guinea and
diversified in multiple migrations, eastward to the Pacific and westward to India
and Africa, in bursts of speciation visible as poorly resolved branches on phylogenies.
Furthermore, some sublineages demonstrate genomic clines that
recapitulate cladogenetic events, suggesting that stepwise geographic speciation,
a neutral process, has been important in Syzygium diversification.
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